code: def on_draw(self, event):
      gloo.clear()
      self.program_v.draw("triangle_strip")
      self.program_s.draw("points")
  
file_path: vispy/examples/demo/gloo/voronoi.py
imports: import numpy
  from vispy import app
  from vispy import gloo
label_desc: Use image node_id 2 for calling the Canvas obj's underlying member method code with example usage: obj.on_draw(event) without return types